Field of the Invention
The present invention relates to a zoom lens and an image pickup apparatus having the zoom lens, and is suitable for a photographic optical system such as a digital still camera, a digital video camera, a TV camera, and a monitoring camera.
Description of the Related Art
Photographic optical systems used for single-lens reflex cameras and video cameras, for example, are required to have high zoom ratios and capability to photograph at high photographing magnification.
Generally, when a photographable object distance is shortened to raise photographing magnification, wide aberration variations occur during focusing, and the ranges of the movements of the focusing lens units widen.
U.S. Patent Application Publication No. 2011/0116174 discusses a zoom lens including, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a fourth lens unit having positive refractive power. In this zoom lens, the second lens unit moves during focusing.
Japanese Patent Application Laid-Open No. 2000-047107 discusses a zoom lens including, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, a fourth lens unit having negative refractive power, a fifth lens unit having positive refractive power, and a sixth lens unit having negative refractive power. In this zoom lens, a floating focus scheme, in which two of the lens units move during focusing, is used.
Japanese Patent Application Laid-Open No. 11-352402 discusses a zoom lens including, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, a fourth lens unit having negative refractive power, a fifth lens unit having positive refractive power. During focusing from an infinite distance to a predetermined finite distance, the third lens unit moves. During focusing on an object distance being shorter than the predetermined finite distance (macrofocusing), the first lens unit moves toward the object side, and the second lens unit moves toward the image side to widen the distance between the first lens unit and the second lens unit. At the same time, the third lens unit moves toward the image side.